Central-energy telephone system.



No. 743,953. PATENTED Nov. 10, 1903.

W. A. TAYLGR.

GEN TRAL ENERGY TELEPHONE SYSTEM.

' Arrmuanou Hum FEB. 4. 1901.

R0 MODEL.

.. g wlr awava 0/ {A f a. la l 'z/ rnz mums PETER-S cc., wxsmmmn. n. c.

UNITED STATES Patented November 10, 1903.

PATENT OFFICE,

WILLIAM .A. TAYLOR, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITGHBOARD AND SUPPLYCOMPANY, OF CHICAGO, ILLINOIS, A.

CORPORATION OF ILLINOIS.

CENTRAL-ENERGY TELEPHONE-SYSTEM.

SPECIFICATION forming part of Letters IPatent No. 743,9 dated Ndvember 1903;

Application filed February 4, 1901. Serial No. 46,897. (No model.)

w an improved form of signal apparatus at the central station.

It has been proposed to provide a telephone system wherein the telephone-lines are adapted to be united for conversation through a repeating-coil, the signal-controlling electroinagnet of each line and the charging source of electricity being bridged between the two limbs of the talking-circuit of the lines; also, to provide means, such as a condenser, for preventing the current from the charging source from passing through the windings of the repeating-coil and controlling the signal controlling electromagnet by the conjoint action of a switch at the substation and a plugseat switch. I

It is the object of the present invention to provide an improved circuit arrangement whereby such plug-seat s witches and the back contacts employed in connection with the supervisory relays may be dispensed with.

I have illustrated my invention in the accompanying drawings, in which Figure 1 isa diagram illustrating two telephone-lines and the central-station apparatus for uniting the same for conversation. Fig.

,2 is a diagram showing the talking-circuits of two connected subscribers. Fig. 3 is adiagram illustrating the relay-windings and the circuit iherethrough.

- Like characters refer to like parts in the several figures.

The telephone-line A extends in two limbs a a to the central station, where said limbs terminate, respectively, in the springs a a the spring a normally resting against back contact 1, which is connected toground, the

spring a normally resting against back coritact 2, which is connected, through individual annunciator c, to conductor 3. The springs a a carry armatures resting opposite the poles of a relay-magnet h, and the spring a when attracted is adapted to engage front contact', which is connected with the linc springs d d. of the spring-jacks or switchsockets d d. attracted to engage contact 5, which is connected with the sleeves d d of the springjacks. Moving with spring a but insulated therefrom, is a spring of, connected to ground through resistance a and adapted when the relay is energized to engage contact 6, which is connected with the test-rings (1 d One end of the winding of relay b is connected with conductor 3, and the other end is connected with the contact-springs d (1 which springs are mounted to move with but insulated from the line'springs d d, respectively. When the plug is inserted in the spring-jack, the spring d is inovedby the tip thereof to carry the spring d into engagement with the grounded contact d.

The subscriber is provided at the su hstation with the usual microphone f, receiver f, and switch-hook f adapted when the line is not in use to engage contact 7, which is connected through bellf to ground. When the telephone is removed from the hook, the hook engages contact 8, which is connected with the telephone transmitter and receiver.

The telephone-line B (shown at the right of the drawings) islike the telephone-line A and is provided with the same parts and mechanism, and like parts have been indicatedby the same reference characters employed in connection with the line 'A.

Theanswering-plug p is provided with a tip 1:) and a sleeve p the former being connected with the strand 2? and the latter with a strand The calling-plugo is provided with a tip 0 and a sleeve 0 the former be- The spring a is adapted when ing connected with a strand t and the latter nected between the windings t and s. In circuit with windings w 20 is a condenser 7,, and in circuit with windings 10 n2 is a condenser Z. Between the strands t and s the windings h and h of a relay h are provided, a battery 1' being interposed between said windings. Likewise between the-strands t and s the windings k and 70 of relay k are connected, the battery 1' being interposed between said windings. The windings of the relays are placed in opposition, so that as the battery-current traverses the same while the lines are connected for conversation the windings will neutralize each other, thereby rendering, the relay inert. The conductors 3, extending to the telephone-lines, are connected with the battery 1", and the opposite pole of said battery is grounded.- Opposite the pole of relay h a spring m is provided carrying an armature and adapted when the relay is energized to engage contact 13. Contact 13 is connected, through the lamp on, with one pole of the battery 1', and the spring 'm is connected with the opposite pole of said battery. Likewise the spring v of relay is is connected with one pole of battery '1', and the contact 15 is connected through lamp 1: tothe opposite pole of saidbat-tery. The windings h and h of the relay h are wound upon the core in such a manner that when the battery-current flows through one of said windings it out over the telephoneline and back through the winding 71 the current will be in such a direction as to neutralize the core. 'lhe'refore while the battery-current flows through both windings the relay It remains unenergized. \Vhen, however, current is passed through one ofthe windings alone, the core will be polarized to attract its armature. Since the windings h and 72 are wound upon opposite ends of the core and are not superimposed, the talking currents will meet impedance, which will prevent the same passing through the windings h 71 The relay thus opposes the passage 7 of the talking-current, is neutralized during the passage of the battery-current through both windings, and is energizedby the passage of the battery-current through one of the windings. The relay k is wound and constructed in the same manner as relay h.

In the strand t a ringing-key g is provided normally resting against contact 17 and adapted when depressed to engage contact l8,which is connected to ground through generator 9. The operators telephone set 71 is adapted to be connected between the strands t ands, and a condenser Z is interposed in the circuit of the telephone set.

Assuming now that subscriber A is desirous of conversing with subscriber B, he lifts his receiver from the telephone hook, thereby closing together limbs a a at the substation. The circuit of battery 1" is thus closed over conductor 3, annunciator 0, contact 2, spring a, limbs a a, spring a contact 1 to the opposite pole of battery 1'. The individual an nunciator c is thus actuated to convey to the operator the signal for connection, and the operator thereupon lifts the answering-plug 17 and inserts the same in the spring-jack belonging to subscriber A. The insertion of the plug moves spring d against cont-act d thereby energizing the relay 1), the circuit through said relay being traced from battery 7', through conductor 3, relay 1), spring (1 contact d to ground, and back to the battery. The relay being thus energized attracts the armatures and moves springs a a out of engagement, respectively, with contacts 1 and 2, thus disconnecting the annnnciator from circuit, and moves said springs into engagement, respectively, withcontacts 4 and 5, thus connecting the terminals of the spring-jacks with the limbs of the telephone-line. The insertion of the answering-plug also connects battery 7' in circuit through the'windings h k of relay h and through the strands t and s of the cordcircuit and the limbs a a of the line. Since the battery-current traverses both of the windings h and h", the core of the relay remains neutral and the relay remains unactuatedl The operator then connects her telephone set t' in circuit in the usual manner and receives the number of the called subscriber. Learning that connection is desired with subscriber B she lifts the answeringplug 0 and touches the tip 0 thereof to the test-ring d belonging to. the spring-jack of subscriber B. It subscriber Bis busy, his relay will be energized and test-ring (1 will be too connected to ground through contact 6 and spring a. If the line be thus busy, the operator upon touching the tip of plug 0 to the test-ring will hear a click in her telephonereceiver; but, on the other hand, if the line he in contact with the test-ring, the battery r is on ,open circuit, and the point t is therefore of the same potential as the pole of the battery. When, however, the tip of the plug is touched to the test-ring, the circuit of battery 7" is closed from ground through the winding is, strand t, tip 0, test-ring (1 contacts 6 and a to ground The resistance thus interposed between the p'ole of the battery and the point. t by the winding it lowers the potential of the point t on closed circuit, and this change of potential of the point 15 with which the operators telephone set is connected, causes a momentary current to flow through the receiver, thereby causing a click therein. As-

called subscriber idle, she inserts the plug 0 therein and then depresses key g, thereby sending current from generator 9 over strand :5, tip 0, spring d, contacts 4 and a limb a, through hell f to ground. When the sub- IIO suming that the operator finds the line of the Patent, is---- scriber responds, he litts the receiver from the hook, thus closing together the limbs a a at the substation. The circuit of battery r is thus closed through windings k strands t s, and limbs a a. Since the current flows through both of the windings of the relay, the relay remains unactuated. The circuits during conversation are shown .in Fig. 2. \Vhen subscriber A is talking and the microphone is act-uated,-variation of the resistance therein causes a corresponding variation of the dilference of potential between the points w and 270', and this variation of difference of potential causes a correspondingly-varying current to traverse the windings w and 20 thereby inducing corresponding currents in windings 20 and 20", which pass through the receiver of subscriber B. Likewise when subscriber 13 is talking the difference of potent-ial between the points y and y is varied, and correspondingly-varying currents will be caused to pass through the receiver of subscriber A. When the subscribers have completed their conversation and desire discounection, they hang up their telephone-receivere, thereby separatinglimbs a a at the sub station and closing circuit from ground over limbs a q], relay-windings 7i and k, battery 7" to ground. Lamps m and 'v' are thus lighted to convey to the operator the signal for disconnection. Thus when subscriber A hangs up his telephone-receiver the circuit of battery 0' is closed from ground through windin g 72-, strand t, limb (t to ground at the substation. But one of the windings of the relay 7: being thus energized, the core thereof is polarized to attract its armature and close together contacts m and. 13, thereby lighting lamp m. Similarly the lamp o is lighted by subscriber B in'hanging up his telephone.

The operator thereupon-removes the plugsp and o from the respective sockets, and the circuit of the battery is opened at the plugterminals and the relays are deenergized to extinguish the lamps. If one of the subscribers should desire an immediate reconnection with another subscriber-,he may by vibrating his switch-hook in the usual manner cause the lamp to be alternately lighted and extinguished to thus convey the signal to the operator for reconnection.

I disclaim herein the matter claimed in the patent to Francis W. Dunbar for'telephoneswitchboard systems, No. 686,272, dated November 12, 1901.

Having described my invention, what I claim.as new, and desireto secure by Letters 1. The combination witha pair of telephonelines, of a repeating-coil through which the same are adapted to be united for conversation, a signal controlling electromagnet bridged between the two limbs of the talking-circuit of one of said lines, said electromagnet having two windings and possessing impedance to the passage of tal king'currents,

a chargingsource of electricity, a switch at l the substationfor closing a complete circuit of said source through one of said windings at one time to actuatesaid magnet or both of said windings at another time, and means for preventingthe passage of the current from said source through the winding of the renet, substantially as described.

2. The combination with a pair of telephonelines, of a repeating-coil through which the same are adapted to be united for conversation, a signal-controlling electromagnet and a charging source of electricity bridged between the two limbs of the talking-circuit of each of said lines, each of said electromaguets having two windings and possessing impedance to the passage of talking-currents, and a switch at each substation for controlor both of the windings of the electromagnet corresponding thereto, and a condenser in circuit with each of the windings of said repeating-coil to prevent the passage of said charging-c u rrent therethrough, substantially as described.

3. The combination with a telephone-line, of a repeating-coil through which the same is adapted to be united with another line, a signal controlling electromagnet bridged be- 4. The combination with a telephone-line,

adapted to be united with another telephoneline, a signal controlling electromagnet bridged between the two limbs of thetalktwo windings and possessing impedance to the passage of talking-currents, a source of and having one pole connected with a third conductor, a switch at the substation for closboth of said windings, or a complete circuit through one of said windings with return through said third conductor tooperate said magnet, and a condenser in circuit withthe winding of said repeating-coil to prevent the closing of the circuit of said source therethrough, substantially as described.

lines, of a repeating-coil through which the same are adapted to be united for conversation, a signal controlling electromagnet bridged between the limbs of the talking-cirpeating-coil associated-with said electromagling the passage of current through one only iug-circuit of one of said lines, and having.

electricity interposed between said-windings- 5. The combination with a pair of telephone tween the two limbs of the talking-circuit of of a repeating-coil through which the same'is ing a complete circuit of said source through &

cuit of one of said lines, said electromagnet having'two differential windings and possessing impedance to the passage of talking-currents, a charging source of electricity, a switch at the substation for closing the circuit of said source over the metallic line and through both of said windings whereby the same is rendered neutral, or for causing an excess flow of current from said source through one winding of said ele'ctromagnet to operate the same, and means for preventing the passage of current from said source through the winding of the repeating-coil associated with said electromagnet, substantially as described.

6. The combination with a pair of telephonelines, of a. repeating-coil through which the same are adapted to be united for conversation, a signal controlling electromagnet bridged between the limbs of the talking-circuit of one of said lines, said electromagnet having two difierential windings and possessing impedance to the passage of talking-currents, a charging source of electricity, a switch at the substation for closing the circuit of said source over the metallic'line and through both of said windings whereby the same is rendered neutral, or for causing an excess flow of current from said source through one winding of said electromagnet to operate the same, and a condenser in 'circuit with the winding of the repeating-coil associated with said electrom agnet and serving to prevent the passage of current from said source through said winding, substantially as described.

7. The combination with a pair of telephonelines, ofa repeating-coil through which the same are adapted to be united for conversation, a signal-controlling electromagnet and a charging source of electricity bridged between the two limbs of the talking-circuit of each of said lines, each of said electromagnets having two dilferential windings and possessing impedance to the passage of the talking-currents, means for permitting current to flow from said source through said windings and 'over the metallic line in a direction to cause said windings to neutralize each other, or to permit an excess flow of current throngh'one of said windings from said source to actuate said magnets, and means in the circuitof each-winding of said repeating-coil to prevent the passage of current from said source but to permit the passsage of the voice-currents, substantially as described.

8. The combination with a pair of telephonelines, ofa repeating-coil through which the same are adapted to be united for conversation, a signal-controlling electromagnet and a charging source of electricity bridged between the two limbs of the talking-circuit of each of said lines, each of said electromagnets having twodifferential windings and possessing impedance to the passage of the talking-currents, means for permitting current to flow from said source through said windings and over the metallic line in a direction to cause said windings to neutralize each other, or to permit an excess flow of current through one of said windings from said source to actuate said magnets, and a condenser in circuit with each of the windings of said repeatingcoil to prevent the passage of current from said source and to permit the passage of voicecurrents, substantially as described.

9. The combination with a telephone-line, of a repeating-coil through which the same is adapted to be united with another line, a signal-controlling electromagnet bridged between the two limbs of the talking-circuit of said line, said electromagnet having two differential windings and possessing impedance to the passage of talking-currents, a source of electricity interposed between the two windings of said electromagnet and adapted to furnish current over the metallic line for conversational purposes, and a hook-switch at the substation forolosing the circuit of said source through both of said windings and over the metallic line during conversation and to close the circuit from said source through one of said windings and suitable return when the conversation is terminated and the switch hook depressed, and a condenser in circuit with the winding of said repeating-coil to prevent the closing of the circuit of said source therethrough, substantially as described.

10. The combination with a telephone-line, of a repeating-coil through which the same is adapted to be united with another telephoneline, a signal controlling electromagnet bridged between the two limbs of the talkingcircuit of one of said lines, said magnet .having two difierential windings and possessing impedance to the passage of talking-currents, a source of electricity connected between said windings and having one pole connected with a third conductor, means at the substation for controlling the flow of current from said source over the metallic line and through both of said windings to cause the same to neutralize each other, on through one of said windings with return through said third conductor to actuate said magnet, and means to prevent the passage of current from said source through the winding of said repeatingcoil, substantially as described.

11. The combination with a telephone-line, of a repeating-coil through which the same is adapted to be united with another telephoneline, a signal controlling electromagnet bridged between the two limbs of the talkingcircuit of one of said lines, said magnet having two difierential windings and possessing impedance to the passage of talking-currents, a source of electricity connected between said windings and having'one pole connected with a third conductor, means at the substation for controlling, the' flow of current from said source over the metallic line and through both of said windings to cause the same to neutralize each other, or through one of said wind- IIO to actuate said magnet, and a condenser in circuit with the winding of said repeating coil to prevent the closing of the. circuit. of said source therethrough, substantially as described.

12. The combination with a telephone-line,

of a repeating-coil through which the same is adapted to be u nitcd with another telephone:

line, a signal-controlling electromagnet bridged between the two limbs of the talkingcircuit of one of said lines, said magnet having two diiferential windings and possessing impedance to the passage of talking-currents, a source of electricity connected between said windings and having one pole connected with a third conductor, a switch at the substation for closing the circuit of said source over the metallic line and through both of said windings whereby said electromagnet is rendered inoperative, or through one of saidwindings with return over said third conductor to actuate said electromagnet, and a condenser in circuit with the winding of said repeatingcoil to prevent the closing of the circuit of said source therethrough, substantially asdescribed.

18. In a telephone system, the combination with telephone-lines, of a cord-circuit to connect said lines together for conversation, a

repeating-coil dividing said circuit condnctively into two parts but inductively uniting them, a condenser in circuit'with'one winding of the repeating-coil to prevent the passage of steady current and permit the passage of voice-cu rrents, a signal-controlling electromagnet bridged across the cord-circuit in par allel with said winding. of the repeating-coil,

' said electromagnet having 'difierential windand means controlled from the substation for connecting the side of the talking-circuit connected with the opposite pole of said source with the said third conductor to unbalance said electromagnet and actuate the same, and a supervisory signal controlled by said elsetromagnet, substantially as described.

14. In a telephone system, the combination with telephone-lines, of acord-circuit to unite said lines for conversation, a repeating-coil interposed in said cord-circuit to conductively separate but inductively unite its two ends, means to prevent the passage of steady current through said windings but to permit the passage oi voice-currents, a differential relay connected with each end of the cordcircuit in parallel with said windings, a source of current interposed between said windings and serving to send current over the metallic line to each substation for conversation when a connection is established by said cord-circuit grounded, a supervisory signal associated with each end of the cord-circuit and con con trolled from the substation after a connection is established to permit current from said source to -flow over the metallic line or over one line only with ground-return whereby in the first instance said relay is inoperative and in the second instance said relay is actuated, substantially as described.

15. In a telephone system, the combination with telephonediucs, of a cord-circuit to unite said lines for conversation, n repeating-coil interposed in said cord-circuit to conductively separate but inductively unite its two ends, means to prevent the passage of steady current through said windings but to permit the connected with each end of the cord-circuit in parallel with said windings, a source of current interposed Y between said winding and serving to send current over the metallic line nection is established by said cdrd-circuit with the lines, said source having one pole grounded, a supervisory signal associated with each end of the cord-circuit and controlled by the corresponding relay, and a switch-hook at each substation for closing circuit over the metallic-line during conversation whereby the relay associated with that line is rendered inoperative orior connecting the proper line-wire to ground at the termination of the conversation to permit current ,from said source to flow through one winding of the corresponding relay to actuate the same tiallyas described.

16. In a telephone system, the combination with telephone-lines, of a cord-circuit to unite said lines for conversation, arepeating-coil interposed in said cord-circuit to conductively separate but inductively unite its two ends, means to prevent the passage of steady current through said windingsbut to permit the passage of voice-currents, a ditterential relay connected with each end of the cord-circuit in parallel with said windings, a source of current interposed between said windings and serving tofsend current over the metallic line to thesubstation for couversatiouwhen a conwith the lines, said source having one pole grounded, a supervisory signal associated with each end of the cord-circuit and controlled by the corresponding relay, a switchhook at each substation, and a signaling-bell normally grounded from one line-wire by said switch-hook, said line-wire being connected with the live pole ofsaid central source of whereby during conversation current flows from said source over the metallic line and renders said relay and supervisory signal inwith the lines, said source having one pole passage of voice-currents, a differential relay current when a connection is established,

trolled by the corresponding relay, and means to the substation for conversation when a conand operate the supervisory signal, substannection is established by said cord-circuit operative, and at the termination of the conversation when the switch-hook is depressed current from said source flows over said line with ground-return to operate said relay and supervisory signal,substantiallyas described.

17. The combination with a pair of telephone-lines, of a repeating-coil through which the same are adapted to be united for conversation, a signal-controlling electromagnet and a separate charging source of electricity bridged between the limbs of the talking-circuit of each of said lines, each of said electromagnets having two differential windings and possessing impedance to the passage of talking-currents, means for permitting current to flow from said source through said windingsand over the corresponding telephone-lines in a direction to cause said windings to neutralize each other, or to permit an excess flow of current through one of the windings of each of said electromagnets from the corresponding source to actuate the said magnets, and means in the circuit of each winding of said repeating-coil to prevent the passage of current from said source but to permit the passage of voice-currents, substantially as described.

18. The combination with a pair of telephone-lines, of a repeating-coil through which the same are adapted to be united for con versation, a signal-controlling electromagnet and a separate charging source ofelectricity bridged between the two limbs of the talkingcircuit of each of said lines, each of said electrom'agnets having two difierential windings and possessing impedance to the passage of the talking-currents, means for permitting the current to flow from said sources through said windings and over .the corresponding telephone-lines in a direction to cause said windings to neutralize each other, or to permit an excess How of current through one of said windings of each electromagnet from the said sources to actuate said magnets, and a condenser in circuit with each of the windingsof said repeating-coil to prevent the passage of current from said source and to permit'the passage of voice-cu rrent,subsi antially as described.

19. The combination with a pair of telephone-liues,0f a repeating-coil through which the same are adapted to be united for conversation, signal-controlling electromagnets bridged between the limbs of the talking-circuit of each line, said magnets having two differential windings and possessing impedance to the passage of talking-currents, a

separate source of electricity interposed between the two windings of the electromagnets and adapted to furnish current over the corresponding metallic telephone-line for conversationalpurposes, a hook-switch at the substation of each line for closing the circuit of the source through both of said windings and over the metallic line during conversation, at which time said electromagnet is rendered inoperative by said current, or to close the circuit from the said source through one of the windings of the electromagnet with suitable return over a third conductor when the conversation is terminated and the switchhook depressed, whereby said electromagnet is operated, and a condenser in circuit with each winding of said repeating-coil to prevent-the closing of the circuit of the said source but to permit the passage of voice-currents, substantially as described.

In witness whereof I have hereunto subscribed my name in the presence of two wit- 

